Inspection of Semiconductor devices have been conventionally carried out as described below. Probes of an inspection substrate are first made in contact with external terminal electrodes of a semiconductor device serving as an inspection target. Subsequently, the inspection substrate is electrically come in contact with the semiconductor device. Inspection of the semiconductor device is thereby carried out. Examples of the probes include a metal lead supported by a flexible substrate, a pin including a coated silicon whisker, a metal pin, or the like.
A first conventional example is a membrane sheet type with metal leads (TAB).
The first conventional example is described in, for example, Japanese Unexamined Patent Publication Nos. 6-334006, 6-334005, 6-331655, and 6-324081. These documents disclose probe structures which are methods of using flexible substrates having metal leads placed in positions opposed to external electrodes of the semiconductor device.
FIG. 1 typically shows a configuration of “a probe card” disclosed in Japanese Unexamined Patent Publication No. 6-334006. In FIG. 1, (A) is a sectional view showing a principal part of a side of the probe card and (B) is a perspective view showing the probe card partly in cross section.
The illustrated probe card has a structure so that a flexible film 23 having a desired inspection circuit pattern and probe pins 3 on a face thereof and that the probe pins 3 come into contact with external electrodes of a semiconductor device 1. The probe pins 3 are arranged at end portions of wiring patterns (not shown), which are supported on the film 23. The wiring patterns, the probe pins 3, and the film 23 integrally form a flexible printed circuit (FPC) 6. Inasmuch as the flexible printed circuit 6 is thin, it is therefore cannot provide a desired contact force discretely. Accordingly, the probe card includes dampers 25 and supporting bodies 29 for supporting the flexible printed circuit 6 at both sides thereof. Therefore, it adopts, as the probe pins 3, structures enable to obtain desired contact.
The supporting bodies 29 are made of stainless steel or brass. The supporting bodies 29 each have a sloped surface, located on the front side (the right side in FIG. 1(A)) thereof, for supporting a portion of the flexible printed circuit 6 that is close to the probe pins 3 and also have a horizontal mounted surface, located on the rear side (the left side in FIG. 1(A)) thereof, for fixing each card substrate. The sloped surface has a trapezoidal shape when viewed from above (see FIG. 1(B)).
The probe card further comprises hard reinforcement plates 28 made of stainless steel and printed circuit boards 27 having wiring patterns on the upper surfaces thereof. The printed circuit boards 27 are reinforced by the reinforcement plates 28 to form a hard card substrate. The dampers 25 each comprises a trapezoidal plate having a short side located on the front side thereof (see FIG. 1(B)). The dampers 25 are fixed above the supporting bodies 29 with bolts 26 in such a manner that insulating sheets 24, the flexible printed circuit 6, and the campers are stacked on the sloped surfaces of the supporting bodies 29 in that order (see FIG. 1(A)). In this configuration, portions of the flexible printed circuit 6 that are close to the probe pins 3 are fixed on the sloped surfaces of the supporting bodies 29 upwards and entire end portions thereof support the probe pins 3 upwards.
A second conventional example is a type using silicon whiskers. The second conventional example is described in, for example, Japanese Unexamined Patent Publication Nos. 10-038918, 2002-257859, and 5-198636.
FIG. 2 typically shows a configuration of “probe pins and a contactor including the same” disclosed in Japanese Unexamined Patent Publication No. 10-038918.
The illustrated probe pin is probe structure of the type which includes a probe pin 3 having structure where a Ni base layer 32 and an Au layer 33 are formed on one grown with a whiskered silicon monocrystal 31 and a Pd layer 34 is formed to the tip thereof. The whiskered silicon monocrystal 31 can be formed in such a manner that an Au seed is disposed on a silicon substrate 30 and then grown by a VLS process. The illustrated probe pin is a probe where a conductive layer is placed on a surface thereof, are used to measure semiconductor devices, and have a probe pin structure in which the tips thereof are covered with a contact material.
A third conventional example is a type using metal pins. The third conventional example is described in, for example, Japanese Unexamined Patent Publication-No. 6-140482.
FIG. 3 shows a configuration of “a probing device” disclosed in Japanese Unexamined Patent Publication No. 6-140482. In FIG. 3, (A) is a perspective view for use in describing a principal part of the probing device and (B) is a sectional view for use in describing a principal part of the probing device.
The illustrated probing device has a probing structure where quartz probe pins 38 and wire probe pins 35 prepared by processing metal pins containing tungsten or the like into fine wires are used together and a structure where the pitch of these pins is small and the probing device can come down in cost.
As shown in FIG. 3, the tungsten wire probe pins 35 are attached to a printed substrate 27 so as to correspond electrodes of a semiconductor device that are arranged at a large pitch (a pitch of 300 to 400 μm) and the quartz probe pins 38 are attached to the printed substrate so as to correspond electrodes of the semiconductor device that are arranged at a small pitch (a pitch of 45 to 65 μm). The quartz probe pins 38 are prepared in such a manner that a tip portion of a quartz sheet 36 is etched and an electrode pattern is formed by plating a surface of the quartz sheet 36 with gold. The quartz probe pins 38 can be used to inspect fine-pitch electrodes, for example, 40 μm pitch electrodes. Inasmuch as the probing device includes the different probe pins separately used depending on the electrode pitch, the probing device can come down in cost as compared to other probing devices including no pins other than quartz probe pins.
The printed substrate 27 has an observation window 37 located at the center thereof. Pattern wires placed on a flexible substrate 6 are electrically connected to contact pins 39 of the printed substrate 27.
However, the first to the third conventional examples have problems below.
Inasmuch as the first conventional example uses, as the base, the film-like flexible material, this example has problems below.
(I-1) It is difficult to control the positional accuracy of the metal leads arranged at a small pitch less than or equal to 40 μm within a desired value (±1.0 μm or less) in a pitch direction because of the thermal history during the manufacture of the film substrate.
(I-2) If a wafer is inspected at a high temperature of 80° C. to 100° C., the metal leads are misaligned with electrodes of semiconductor devices because a film material has a thermal expansion coefficient (several tens ppm) greater than the thermal expansion coefficient (2 to 3 ppm) of silicon as material of the semiconductor devices.
Inasmuch as the probe pins used in the first conventional example are made of a single elastic metal material that has not been selected depending on a material of a contact target, this example further has a problem below.
(I-3) It is difficult to obtain good contact properties in some cases.
Inasmuch as the second conventional example has structure where the pin including the coated whiskered silicon monocrystal make contact with the external electrode of the semiconductor device, the second conventional example has problems below.
It is assumed that pins with a diameter of about 10 μm are formed so as to match electrodes arranged at a pitch of 40 μm or less, for example, a pitch of 20 μm. In this case, it is very difficult to provide gold bumps on Si mesas before growing pins, a stress is created during the formation of a metal layer, and damage is caused in a process of trimming the tips after forming the pins, Therefore, there are problems below.
(II-1) It is difficult to secure the positional accuracy to cope with the electrode pitch of the semiconductor devices.
(II-2) Inasmuch as the diameter of the pins is very small, the pins are broken by overdriving because the strength of the pins is low.
Inasmuch as the Si pins used in the second conventional example are entirely covered with metal layers in order to obtain conductivity and the tips of the Si pins have metal films thereon, this example further has a problem below.
(II-3) The cost thereof is high.
The third conventional example has structure where the tungsten wire probe pins and the quartz probe pins making contact with the external electrodes of the semiconductor devices are separately used depending on the electrode pitch. In order to inspect electrodes arranged at a small pitch, for example, a pitch of 40 μm or less, the wire probe pins must have a diameter of 20 μm or less; hence, this example has a problem below.
(III-1) It is very difficult in manufacture. If possible, it is very difficult to arrange the pins with high accuracy. Furthermore, there is a problem in that the pins have low strength.
The third conventional example further has problems, as described below, due to the stress created by forming the metal layers on the quartz probe pins as well as the silicon probe pins of the second conventional example.
(III-2) It is difficult to secure the positional accuracy to cope with the electrode pitch of the semiconductor devices.
(III-3) Inasmuch as the diameter of the pins is very small, the pins are broken by overdriving because the strength of the pins is low.
In a case where the third conventional example includes no pins other than the quartz probe pins, this example further has a problem below.
(III-4) The cost thereof is high.
Furthermore, even if the pins are used such that that the pins are not broken by overdriving, the second and third conventional examples have a common problem below.
(III-5) It is impossible to secure the durability of the pins for practical use.
Accordingly, it is an object of the present invention to provide a practical inspection probe useful in inspecting semiconductor devices with a small electrode pitch.